58 SEPTEMBER 2016 • WORLD AQUACULTURE • WWW.WAS.ORG KOH, oxidase, catalase, motility, growth in NaCl and sensitivity to the vibriostatic agent 0/129 showed that they were Gram-negative colonies, all short bacilli that were sensitive to the vibriostatic agent 0/129 and all characteristics that place them among Vibrio bacteria. DNA analysis of the 16S rDNA gene sequence corroborated that the bacteria present in the dark blisters and organic deposits belong to the genus Vibrio; and that the majority of them are considered to be part of the clade or group Splendidus (Table 1); within this clade, bacteria such as V. splendidus is able to cause secondary infections in soft tissue. Members of the genus Vibrio have been described as opportunistic pathogens affecting all life-cycle stages of bivalve mollusks from larvae to adult (Allam et al. 2002). Vibrio tasmaniensis, V. splendidus and V. neptunius are species that are distributed throughout the world, associated with aquaculture, and are causative agents of diseases in aquatic organisms when environmental conditions are favorable (Thompson et al. 2003, Guisande 2004). In particular, strains of V. splendidus and related species V. harveyi and V. tapetis have been related to “shell disease” in bivalve mollusks (Paillard et al. 2004). These diseases are characterized by the abnormal production of deposits of organic matter on the inner surface of the valves and a brown coloration of the mantle tissue that comes in contact with deposits of organic matter. This study revealed a typical case of the presence of boring polychaetes and associated opportunistic bacteria in red abalone cultured in Mexico. To contribute to their control, the correct management practices at appropriate times need to be carried out, including maintaining a visual surveillance program for early detection of infested abalones. This can be done during feeding and/or during clearing of the juvenile population and growth monitoring. All infested abalones must be removed from culture tanks and disposed inland, where they must be sacrificed, dried and ideally buried or incinerated. A good filtration system is necessary to avoid dispersion of planktonic larvae during spawning periods as well as for removing small crawling stages or fractionated worms dispersed by currents or handling. The removal of solid wastes from the bottom of culture tanks is essential. The removal of empty shells from the system may aid in preventing infestation by these worms. Moreover, high water quality standards and a regular bacteriological analysis may aid in guaranteeing low levels of opportunistic bacteria. Training on good sanitary practices of all workers involved in aquaculture production is an essential step for avoiding these type of disease outbreaks. Acknowledgments This project was supported by the Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE) and the Instituto de Sanidad Acuícola (ISA). Notes Jorge Cáceres-Martínez*, Yessica Hernández-Mercado, Roberto Cruz-Flores and Montserrat Muñoz-Flores. Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE). Carretera Ensenada-Tijuana No. 3918, Zona Playitas, 22860. Ensenada, Baja California, México * Corresponding author: jcaceres@cicese.mx Rebeca Vásquez-Yeomans. Instituto de Sanidad Acuícola, A.C. (ISA). Calle de la Marina S/N. esq. Caracoles, Fraccionamiento Playa Ensenada, 22880. Ensenada, Baja California, México. References Allam, B., C. Paillard and S.E. Ford. 2002. Pathogenicity of Vibrio tapetis, the etiological agent of brown ring disease in clams. Diseases of Aquatic Organisms 48:221-231. Guisande, J.A., M. Montes, R. Farto, S.P. Armada, M.J. Pérez and T.P. Nieto. 2004. A set of tests for the phenotypic identification of culturable bacteria associated with Galician bivalve mollusk production. Journal of Shellfish Resources 23:599-610. Lleonart, M., J. Handlinger and M. Powell. 2003. Spionid mudworm infestation of farmed abalone (Haliotis spp.). Aquaculture Magazine 221(1):85-96. Paillard C., F. Le Roux and J.J. Borrego. 2004. Bacterial disease in marine bivalves, a review of recent studies: trends and evolution. Aquatic Living Resources 17:477-498. Simon, C.A., A. Ludford and S. Wynne. 2006. Spionid polychaetes infesting cultured abalone Haliotis midae in South Africa. African Journal of Marine Science 28(1):167-171. Thompson, F.L., C.C. Thompson, Y. Li, B. Gómez-Gil, J. Vandenberghe, B. Hoste and J. Swings. 2003. Vibrio kanaloae sp. nov., Vibrio pomeroyi sp. nov. and Vibrio chagasii sp. nov., from sea water and marine animals. International Journal of Systematic and Evolutionary Microbiology 53:753-759. Tinoco-Orta, G.D. and J. Cáceres-Martínez. 2003. Infestation of the clam Chione fluctifraga by the burrowing worm Polydora sp nov. in laboratory conditions. Journal of Invertebrate Pathology 83:196-205. TABLE 1. Comparison of sequences in GenBank by BLAST (Basic Local Aligment Search Tool) obtained from bacterial isolates of chitinous and organic matter of blisters formed by Boccardia proboscidea using 16S rDNA recovered from Haliotis rufescens. GenBank Species Similitude Identity access number (%) (%) MNR_117891.1 Vibrio chagasii 100 99 NR_074953.1 Vibrio splendidus 100 99 NR_044078.1 Vibrio crassostreae 99 98 NR_115806.1 Vibrio cyclitrophicus 100 99 NR_116067.1 Vibrio atlanticus 100 99 NR_036929.1 Vibrio tasmaniensis 100 99 These burrowing worms have several biological characteristics that make their control difficult. The reproductive strategies of these species make them powerful invaders that are difficult to eradicate if they are allowed to spread in aquaculture facilities.
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